Several years ago two patents were issued on an abrasive material made from electric arc furnace dust. These patents were U.S. Pat. Nos. 5,964,911 and 6,057,257 (filed in the names of Gerald P. Balcar and James Morano); the entire disclosure of each of these patents is hereby incorporated by reference into this specification. In the remainder of this specification, these patents will be referred to as the “Balcar patents.”
The Balcar patents described a composition that contained at least 60 weight percent of ferrometasilicate. Thus, e.g., at lines 18-29 of column 3 of U.S. Pat. No. 6,057,257, it is disclosed that “The abrasive composition of this invention is comprised of at least about 60 weight percent of ferrometasilicate, which has the formula FeSi03. This iron compound is well known in the art and is described, e.g., in U.S. Pat. Nos. 5,326,526, 4,604,140, 4,519,811, 4,205,392, 3,650,802, 3,616,041, and the like.”
U.S. Pat. No. 5,981,413 of Roland D. Hale issued at about the same time as the Balcar patents, and it also related to the same abrasive composition. The Hale patent, however, did not specify the amount of ferrometasilicate that was present in its claimed composition.
During the latter part of the 1990's, Estech of Hollywood, Fla. sold a composition made in accordance with the teachings of the Balcar patents and the Hale patent under the name of “Vetroblast.” In a sales brochure dated Jan. 3, 2002, entitled “Vetroblast Fast Acting Blasting Abrasive,” it is disclosed that such abrasive was “ . . . a unique glass-ceramic . . . “whose” . . . base material is composed of ferrosilicate crystals with randomly dispersed spinels in a vitreous matrix.” In the “Components Information” section of this brochure, it is disclosed that “Vetroblast” is comprised of 35 weight percent of silicon dioxide (Si02) and 35 weight percent of iron oxide (“Fe203/Fe304”).
The “Vetroblast” material is substantially inferior to the material made by the process of the instant invention. Thus, e.g., the “Vetroblast” material is not sufficiently durable, being unsuitable for many repeated uses as a blasting abrasive; applicants' composition, by comparison, can be repeatedly used as blasting abrasive without losing effectiveness. Thus, e.g., applicant's composition may be used a closed circuit blasting abrasive as well as an open blasting abrasive product. In addition, the composition of the instant invention contains a relatively high percentage of blocky shaped particles down to small particle sizes (63 microns or less).
Without wishing to be bound to any particular theory, applicant believes that the presence of a substantial amount of ferrometasilicate in the prior art “Vetroblast” loose grain blasting abrasive material adversely affected the properties of such abrasive. It is not believed that such “Vetroblast” was a commercial success; it is not being sold today.
It is an object of this invention to provide a novel abrasive composition that is substantially superior to the “Vetroblast” abrasive composition.